Dual sensor motion detection systems are quite common and various arrangements have been proposed for processing the signals of such dual sensor motion detection systems to reduce the possibility of false alarms. An alarm signal is normally only produced when both sensors confirm within a particular time period the presence of motion or a body in the room. Some systems, further process the signals whereby if a certain sensor is determined as having failed, the system produces a trouble indication or possibly an alarm when the one active sensor is activated or has been activated a number of times.
Other arrangements for processing signals in a motion detection system having at least two sensors are shown in U.S. Pat. No. 4,710,750 (Johnson), U.S. Pat. No. 4,195,286 (Galvin), U.S. Pat. No. 4,611,197 (Sansky), and U.S. Pat. No. 4,833,450 (Buccola et al).
Such systems, when installed, have the sensors adjusted to a certain sensitivity and in some cases where the system is oversensitive, an installer must return to the installation and readjust the system.
There remains a need for a simple system which is easy to install and is easy to operate by the end user.